OL issues are always more complex than they first appear.
Consistency and coordination between the players is critical. If one guy is not doing his job, it makes the job of the guy next to him more difficult, often also appearing to be not doing his job.
Shuffling guys in and out of the lineup also hurts performance, even if they are both capable. It takes some time to develop the chemistry to make things work.
Right now the weak link is clearly David Baas, and there is nothing we have seen in the last three years to indicate that is going to be solved any time soon. However, in fairness, he missed most of training camp with an injury and now has an ankle sprain. Still, he has never been the most agile guy nor does he have the quickness one needs to trap or pull effectively. He was a huge bulldozer-type that Nolan wanted, and that is about all he is.
Rachal is really about 1/3 of the way through his rookie year after coming out a year early. He has had some nice games but the Ram games was his low point. We should allow him some time to develop.
But there is another thing that is troublesome and that is the design of the offense: Opposing teams are loading the middle of the box and that, combined with the poor play of Baas, is making it hard to run. More misdirection and counter plays would help but first...the team needs to start hitting some quick passing plays - slants and curls behind the linebackers. Until Raye starts forcing the LBs to drop off the line, the OL issues will not look any better. Hill can through middle distance well enough to force some respect but the ball must come out sooner. I don't know if Morgan is the guy or if someone else must step up but the current WRs don't seem to be getting open soon enough. In general, this offense needs an enema - get rid of the stuff that is just things up. We saw a bit of that in the second half but there must be a lot more against Atlanta if this team is to compete in the next four games...and after that, it won't get any easier.
In summary, the OL will appear stronger if the offensive design becomes more varied to take the pressure off a couple of guys who are struggling right now - that is what good coaching is supposed to do. You don't have to have All Pros at every position to win. The 49ers won their first Super Bowl with a very forgettable Dan Audick at tackle. The next year he was out of the league but Walsh's offense protected him and used his limited abilities to best advantage. That is the kind of thing Raye/Singletary will need to do if Baas is to be useful. Rachal will be fine with more time, IMO, but will need help in the meantime.